1. Field of the Invention
This gating system is to be applied to any type of mold poured by gravity such as sand based, graphite based, metallic based, or a combination of different materials, etc., for pouring any metal compatible with the refractority and resistance of the materials available for making the skin-strainers, and for pouring castings with a wide range of size and shape.
2. Description of the Prior Art
When pouring a mold, through the gating system the flow of metal is controlled in order of avoiding turbulences and inclusions, and in order to properly fill the entire mold. After the mold filling is finished the gating system, if properly designed, promotes a good directional solidification through the casting.
Different types of gating systems are usually implemented. Examples of these are given in FIGS. 1 and 2 which figures have been established by the American Foundrymen's Society in order to illustrate the different parts of a gating system.
The gating systems presently in common use generally solve the problem of obtaining sound castings but at the same time very frequently present some adverse economical aspects which are:
1. Relatively high proportion of metal involved in the gating system. PA1 2. Increased mold volume for accommodating the gating system. PA1 3. Finishing operations for separating the gating system from the casting. PA1 4. Creation of obstacles while the casting is cooling and contracting, which promotes deformations and internal stresses in the casting. PA1 1. The skin-strainer which is always present. PA1 2. The overhead melt distributor which use depends on the casting configuration. PA1 1. To control, which means to restrict to any required degree the flow of metal or alloy being poured into a gravity foundry mold. PA1 2. To limit sharply or even avoid melt turbulences inside the mold casting cavity, which turbulences most generally are casting defect generators. The effect of this gating system on the metal flow is similar to the one produced by the filter used at the kitchen sink to avoid splashings. PA1 3. To limit sharply or even avoid the entry of any detrimental melt inclusions into the inside of the mold casting cavity. PA1 4. To allow when necessary an adequate venting of the mold casting cavity around the ingate which venting often is difficult to achieve, mainly for metallic molds. PA1 5. To assure the desired directional solidification of the casting and its gating system. PA1 6. To provide the gating system with a minimum volume thus allowing the pouring of more molds per melt batch. PA1 7. To minimize or even eliminate the fettling operations originated by the gating system. PA1 8. To reduce the molding cost by using a more compact gating system which requires smaller molding boxes and allows more molds in the same molding area. PA1 9. To reduce the internal stresses and deformations associated with the casting solidification and cooling, by minimizing the connections between the casting and its gating system. PA1 increase of the castings soundness, PA1 dropping of the % of rejects PA1 decrease of the castings cost.
The aim of the present invention is to diminish the importance of these adverse aspects or even eliminate some of them but still keeping and even improving the conditions for producing a sound casting.